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div/rem by zero and div/rem overflow are both undefined according to

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langref.  Constant fold them to undef instead of trying to preserve
the trap.  This fixes PR3354.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62534 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-01-19 21:55:26 +00:00
parent dbe664adcd
commit c9a005807a
1 changed files with 11 additions and 11 deletions
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22
lib/VMCore/ConstantFold.cpp
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@ -655,11 +655,15 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
case Instruction::SDiv:
if (CI2->equalsInt(1))
return const_cast<Constant*>(C1); // X / 1 == X
if (CI2->equalsInt(0))
return UndefValue::get(CI2->getType()); // X / 0 == undef
break;
case Instruction::URem:
case Instruction::SRem:
if (CI2->equalsInt(1))
return Constant::getNullValue(CI2->getType()); // X % 1 == 0
if (CI2->equalsInt(0))
return UndefValue::get(CI2->getType()); // X % 0 == undef
break;
case Instruction::And:
if (CI2->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
@ -733,24 +737,20 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
case Instruction::Mul:
return ConstantInt::get(C1V * C2V);
case Instruction::UDiv:
if (CI2->isNullValue())
return 0; // X / 0 -> can't fold
assert(!CI2->isNullValue() && "Div by zero handled above");
return ConstantInt::get(C1V.udiv(C2V));
case Instruction::SDiv:
if (CI2->isNullValue())
return 0; // X / 0 -> can't fold
assert(!CI2->isNullValue() && "Div by zero handled above");
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
return 0; // MIN_INT / -1 -> overflow
return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef
return ConstantInt::get(C1V.sdiv(C2V));
case Instruction::URem:
if (C2->isNullValue())
return 0; // X / 0 -> can't fold
assert(!CI2->isNullValue() && "Div by zero handled above");
return ConstantInt::get(C1V.urem(C2V));
case Instruction::SRem:
if (CI2->isNullValue())
return 0; // X % 0 -> can't fold
case Instruction::SRem:
assert(!CI2->isNullValue() && "Div by zero handled above");
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
return 0; // MIN_INT % -1 -> overflow
return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef
return ConstantInt::get(C1V.srem(C2V));
case Instruction::And:
return ConstantInt::get(C1V & C2V);